Jozani biodiversity inventory report 2002 - Coastal Forests of Kenya ...

60
50
53.49
49.06
Basal area (m 2 .ha -1 )
40
30
20
10
0
36.57
22.35
16.30
16.98
17.01
8.43
4.89
0.02
1.20 1.37
4.75 4.09
5.23 6.32 3.29
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Transects
Figure 2: Basal area in different transects representing various vegetation types in Jozani-
Chwaka Bay proposed National Park, Zanzibar
iii) DBH and height distribution
One way of assessing forest structure is by looking at the way individuals of different sizes
(height and stem diameter) are represented in that community. The height frequency distribution
is presented in Fig. 3 & Table 5 while DBH frequency distribution for various transects
representing different vegetation types is shown in Fig. 4 and Table 5. For all trees sampled in
each transect there was highest number of plants in the lowest DBH class (i.e.10.0-14.9cm) and
the lowest number in the largest DBH class except for transect 8 (ground water forest: Pandanus
–Elaeis dominant) and transect 9 (Callophylum plantation) in which the opposite pattern was
observed. Again with exception of transects 8 and 9 there was a consistent decrease of number of
individual per class as DBH increased. This dominance of trees in the lower DBH classes as
observed in this study is a good indication of active forest regeneration since many tree
populations have small newly recruited individuals differing in size and age. The opposite trend
observed in transects 8 and 9 where many individuals are found in the largest class is an indicator
of low or lack of forest regeneration process. This observation shows that there is not much
regeneration taking place in the Callophylum plantation nor in Pandanus-Elaies stand in the
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